By Mai Nguyen

HANOI (Reuters) – African swine fever has been detected on three farms in Vietnam, authorities said on Tuesday, the first confirmed cases of the highly contagious disease in the Southeast Asia country.

All pigs on the farms located in Hung Yen and Thai Binh provinces, southeast of the capital Hanoi, were culled, the Animal Health Department said in a statement.

The disease, which is incurable in pigs but harmless for humans, has spread rapidly across neighboring China since August, affecting 25 provinces and regions.

“The disease is not infectious for humans, so people and farmers shouldn’t panic,” Pham Van Dong, head of the department, told a press conference in Hanoi.

Pork accounts for three quarters of total meat consumption in Vietnam, a country of 95 million people where most of its 30 million farm-raised pigs are consumed domestically.

“Consumers can continue to use (pork) products and shouldn’t boycott these products,” Dong said.

With pork such a popular meat in many Asian countries, U.N. experts said last September the spread of the virus to China’s neighbors was a near certainty, and likely through movements of products containing infected pork.

Nguyen Van Long, the department’s chief of epidemiology, said smuggling of animals across borders and tourism made it difficult to control the spread of the disease.

Taiwan’s official Central News Agency reported on Friday that the country’s Council of Agriculture had found the virus in a sandwich carried from Vietnam to Taiwan on Feb. 5.

Authorities in Taiwan and Vietnam are working to determine the origin of the pork found in the sandwich, Vietnam’s animal health department said.

(Reporting by Mai Nguyen; writing by Khanh Vu; additional reporting by Yi-Mou Lee in Taipei; editing by Darren Schuettler)